GEEK CLUB: The script called for Michael Emerson to come up with a physical handicap for his “Person of Interest” character, Harold Finch. Photo:

GEEK CLUB: The script called for Michael Emerson to come up with a physical handicap for his “Person of Interest” character, Harold Finch. (
)

Greenpoint is a home away from home for the CBS hit drama “Person of Interest.”

It has enough long dark alleys — like the infamous Kent Street dead end — and desolate street corners to allow producers to convey urban menace against the glittering backdrop of the Manhattan skyline.

On a warm night in October, the show has set up shop on the lonely corner at the intersection of Manhattan Avenue and Ash Street, within sniffing distance of Newtown Creek.

A dozen or so takes are required to supply the necessary close-ups and reaction shots.

In between two of them, Jim Caviezel, who plays the raspy-voice avenger Reese, drops to the sidewalk and does a dozen push-ups.

Michael Emerson says that “Person of Interest” compresses something like 100 hours of shooting, on location all over New York City, and in a Long Island City studio, into 43 minutes of television each week.

With a 10-month production schedule, it’s a demanding job, to say the least, but Emerson, 58, isn’t one to complain.

He gets to live again in New York, the home he had to leave for five years while he was playing Ben Linus, his Emmy-winning role on ABC’s “Lost.”

Sitting in a director’s chair on the corner of Ash Street, across the street from a building in the cinder-block stage of construction, Emerson, 58, says he was only supposed to work on the “Lost” Hawaii set for three episodes so he “packed light.”

And then the producers “never let me come home.”

Welcome to the life of a TV star. And with “Person of Interest,” that’s what Emerson has become.

Not only did he never imagine something like this would happen, he has hardly had the time to enjoy it. He’s too busy working.

“I never even thought of the world offstage. I had started so late,” says Emerson, who began acting when he was in his 40s after an unsatisfying career as a magazine illustrator. “And the theater was all I knew.

“I didn’t even know how you got from the world of the stage to the world of the camera. It turns out you don’t have to worry about it. It will either happen or it will not.”

With his understated yet spooky presence and precise diction, Emerson was a natural for the all-knowing Finch, who created The Machine, the real star of “Person of Interest.”

When he read the pilot script, he did not smell a hit.

“An actor steels himself against the real possibility of the pilot not being picked up. And then you’re back, looking for work again,” he says.

“I wasn’t quite ready for it getting the green light and going, and finding an audience. All of that is kind of breathtaking.

“I just thought: What are the chances that you could be on two successful, one-hour dramas in a row? It really never happens.”

Emerson’s co-star, Kevin Chapman, who plays Det. Fusco, walks by and says, “Hey, Miguel” before hitting the snack bar at nearby craft services. Miguel is the last nickname you’d pick for Emerson, who is every bit as refined and articulate as Finch, without the creepy charisma.

That comes out on screen, as does the limp he uses for the character, something he cooked up because the character needed an infirmity.

“I thought, ‘Let’s be careful because God forbid this thing is successful,’ ” he says. “It should be effective without being torturous so I don’t end up needing physical therapy.

“I fiddled around at home. And I thought having a leg that you can’t control, that’s easy enough. And I think I can remember not to turn my head. I’ve trained myself so well now that it’s harder for me not to do it than to do it.

“What I have trouble with is when we shoot flashback scenes. Before his injuries. I have to pinch myself and try to stay loose.”

Finch has had a beefed-up story line on “Person of Interest” this year. He was kidnapped at the end of last season by an adversary named Root (Amy Acker) and rescued. Now he has to deal with the scope of The Machine.

“They’ve already begun in an odd way to make The Machine a character,” he says. “And we saw in those early episodes Mr. Finch training a sort of intimate machine, putting it through its earliest and most rudimentary paces. We’re going to see that The Machine is highly sophisticated and has a personality of its own, which will be interesting to explore.”